<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title></title>
	<style type="text/css">
		body {
			background-color: #f0f0f0;
			/*display: flex;
			min-height: 100vh;
			margin: 0;*/
		}
		.container {
			width: 100px;
			height: 100px;
			line-height: 100px;
			position: absolute;
			left: 50%;
			top: 50%;
			margin-left: -50px;
			margin-top: -50px;
			background-color: #ccc;
		}

	</style>
</head>
<body>
	<div class="container">
		我垂直居中啦<br/>
	</div>
</body>
</html>